Perl

Perl – Practical Extraction and Report Language is a free high-level, interpreted, dynamic programming language written by Larry Wall in the year 1987.Perl is very good for shell scripting and regualar expression.If you use GNU/Linux is default installed, on windows you have to install ActivePerl.The languages includes Perl 5 and 6, I use primary Perl 5(Perl 5 is also continue developing).The symbol of the Perl language is the Camel symbol.

Variable

$ for Scalar,@ for Array and % for Hashes, as example:

my $name = "test";
my @name = ("test1","test2");
my %name = ("key1" => "test1","key2" => "test2");

my $name = "test";

my @name = ("test1","test2");

my %name = ("key1" => "test1","key2" => "test2");

In Perl all variables are Scalars, you could store numbers and strings in the same value without convert.If you want to add a Scalar to another you have to concate two strings with “.”, but if you want to add two number you should use “+”.To access an element from the array you could use “$name[0]”, it starts from 0 to the last element, you get the last element with “$#name”.For manipulating a Perl Array look at this Post.And you could choose in a big list of default variables.

Quoting

Be careful with quoting, the double quotes could interpolate other Scalars.

my $a     = "1";
my $name1 = "$a";
my $name2 = '$a';

my $a = "1";

my $name1 = "$a";

my $name2 = '$a';

The name1 is “1” and name2 is “$a”.

Print

an simple “Hello World!” example:

print "Hello World!\n";

1	print "Hello World!\n";

Comparison

To compare the Scalars you could use them from this table:

compare type	number	string
equal	==	eq
not equal	!=	ne
less than	<	lt
greater than	>	gt
less or equal	<=	le
greater or equal	>=	ge

loops

In Perl are more than one way to make a loop:

for(1..10){...}
for(my $i=1;$i<=10;$i++){..}

1 2	for(1..10){...} for(my $i=1;$i<=10;$i++){..}

the first one is faster and faster to write, but the second has more possibility’s to change.

Do-While loop:

do
{
   ...
}while(1);

{

...

}while(1);

While loop:

while(1)
{
   ...
}

while(1)

{

...

}

Regex

Regular Expressions are very good implemented by Perl:

$x =~ s/a/b/og;

if($x =~ /b/){
...
}

$x =~ s/a/b/og;

if($x =~ /b/){

...

}

Optimizing

Perl is an interpreted language and if you need more performance you could use Inline code like C or you could take a look at my Benchmarks or at write fast code in Perl.

If you want to see some examples and solution from me see into my Category – Perl or if you want to see some special Tricks in Perl.

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